Medical device adhering to the skin

ABSTRACT

The present invention relates to a medical device adhering to the skin comprising a housing with a rigid base fixable on a patient&#39;s skin by means of an adhesive layer which has an adhesive surface, essentially co-extensive with the base, contacting the skin and which is fixed to the base by a reduced surface in comparison to the adhesive surface contacting the skin.

BACKGROUND

1. Field of the Invention

The invention relates to a medical device comprising a housing with arigid base which is fixed on the patient's skin by means of an adhesivelayer for temporary wearing on the body.

2. Related Art

Devices of this kind are, for example, transducers or transdermalinjection or infusion devices, etc. In order to fix them, theapplication surface is provided with an adhesive coating which isusually annular and has an outside diameter corresponding to the device.

The adhesive layers usually adhere to the skin very well, but if thedevice is worn for any length of time and is subject to appreciablemovement the adhesive layer becomes detached starting from the edge.

Attempts have been made to counteract this by increasing the adhesivesurface, so that its outside diameter is larger than that of the device.However, this also has disadvantages, so that no satisfactory solutionof the problem has hitherto been found.

The object of the invention is to solve this problem.

SUMMARY OF THE INVENTION

To this end, according to the invention, the adhesive layer is fixed tothe device by a reduced surface in comparison with the adhesive surfacefacing the skin. Preferably, this gives an outer annular zone of theadhesive layer where the latter is not connected to the device.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a cross sectional view of the medical device of the presentinvention.

FIG. 2 shows a schematic representation of the housing of the medicaldevice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

One exemplified embodiment of the invention is described hereinafterwith reference to the accompanying drawing.

FIGS. 1 and 2 are diagrams of a transdermal injection system worn on thepatient's skin for a given time, e.g. a number of days. The injectionmechanism including the pump and active substance reservoir is locatedin a housing 1. The latter is fixed on the patient's skin H by means ofan adhesive layer 2. The adhesive surface 3 of the adhesive layer is ofthe same size as the underside of the housing 1. The surface by whichthe adhesive layer is fixed on the housing 1 on the side remote from theadhesive surface 3 is smaller than the latter. The adhesive layer a isnot connected to the housing 1 in an outer zone 4. This zone is annularand extends from the outer edge inwardly by about 5 to 10 mm.

It has been found that this configuration does not result in detachmentfrom the skin even when worn for long periods and subjected to extensivemovement.

What is claimed is:
 1. A transdermal injection system for administeringan active substance to a patient adapted to be affixed to a skin surfaceof the patient including a housing, said housing including an injectionmechanism having a pump and an active substance reservoir therein, saidhousing defining a rigid base having a size, and one adhesive layerinterposed between said rigid base of said housing and adapted foradhering to a patient's skin for adhesively affixing said injectionsystem to the patient's skin wherein the improvement comprises: a firstadhesive surface of said one adhesive layer adjacent to and adapted tobe adherent to the skin of the patient having an equivalent size to saidsize of said rigid base of said housing, and a second adhesive surfaceof said adhesive layer adjacent to and adherent to said rigid base ofsaid housing, wherein said second adhesive surface having a reducedsurface in comparison with said first adhesive surface, wherein saidreduced surface defines an annular zone extending from an edge of saidreduced surface a distance between about five to about ten mm to anouter edge of said housing, and wherein said adhesive layer is notconnected to said housing in said annular zone, thereby capable ofsubstantially reducing an inadvertent detachment of said first adhesivesurface from the skin of the patient.
 2. A transdermal injection systemfor administering an active substance to a patient adapted to be affixedto the skin of the patient's body comprising: a housing including aninjection mechanism having a pump and an active substance reservoirtherewithin, said housing defining a rigid base having a size; oneadhesive layer interposed between said rigid base of said housing andadapted for adhering to the patient's skin for adhesively affixing saidinjection system, wherein a first adhesive surface of said adhesivelayer, adjacent to and adapted to be adherent to the skin of thepatient, has an equivalent size to said size of said rigid base of saidhousing; and a second adhesive surface of said adhesive layer adjacentto and adherent to said rigid base of said housing, wherein said secondadhesive surface having a reduced surface in comparison with said firstadhesive surface, wherein said reduced surface defines an annular zoneextending from an edge of said reduced surface a distance between aboutfive to about ten mm to an outer edge of said housing, and wherein saidadhesive later is not connected to said housing in said annular zone,thereby capable of substantially reducing an inadvertent detachment ofsaid first adhesive surface from the skin of the patient.